Road Tyre advice (for a newbie)

Cheers froze, makes me happier knowing the liners are plastic. Unlike rubbish, they contour well, remain within tyre and will easily find the recycling bin later; much later. They will hot pot recycle easy.
As too cutting liners, I wouldn't bother as overlap doesn't harm performance and the slight weight is nearer nothing compared to the other side of the circle when used to counter reflector or such.
Anyway, congratulations with cycling Psyche, I'm wondering if the Brits will let me migrate. Paddling holy head to isle of Mann would be a loveable chore. Last time I visited a tropical cousin of great white washed up on a cold Devon beach. I thought it was funny because when the destroyer class ship was locally launched, my friends son; a disendant of Sir Lancealot rolled into the water and a copper boat plucked him from. Then 2 months later a great white 4.5 leapt from waters in front of camera/s.
I'm amazed, I had been walking around about 10-20 years thinking everyone was a wizard yet hid such such like sex.
Cycling /walking/canoeing/swimming; concentrated exercise is best in case incoming incoming.
Nice high rocks where some of you guys live, perfect too incubate a dragon.
Psyched ya; enjoy brother.
Trumps a champion

Really pleased you enjoyed it! You might want to edit your post though, 25 meters isn't that impressive around here ​.

I would not go with Conti 4 Seasons or other such high priced Contis, why? because there are a lot of tires on the market today that are just as good, if not better, for at least a third of the cost for Conti's.  And the Conti Ultrasport don't even have flat protection in them, what did you expect for $9?  At least with a Schwalbe Lugano K-Guard folding tire it has a flat protection belt and it only cost $15.  The prices I'm quoting came from Ribbles based on US dollar.

Now on to liners, Mr Tuffy are not kevlar or aramid they are polyurethane, not that it really matters but poly seems to work better then kevlar or aramid but at a cost of more weight.  I don't like Mr Tuffy because they don't trim the ends smooth so they don't rub a hole into the tube as you ride, I aways had to sand down the ends myself to prevent that.  Now a newer liner called RhinoDillos have put a soft plyable end on their liner which prevents the liner from rubbing a hole into the tube, and from reviews and test they may be better at stopping flats then the Mr Tuffy.

Don't waste your money on thorn resistant tubes, they had a lot of weight to a wheel and do very little to stop flats, so just use your normal tubes, a decent tire, and a liner if you want to have miles of virtual flat free riding.  Almost forgot, always add talic or baby powder to tubes before installing, this actually decreases rolling resistance a tad.

A general 'average' is 40-42 mm for non-aero rims.

I use those inner tubes & also run 25c tyres,  although whilst they're £6 at Halfords, half that price at either of these shops... (depending upon where is easiest for you to get to - Evans have shops all over the UK)

https://www.sigmasports.com/item/Continental/Race-28-Inner-Tube-700x18-2...

https://www.evanscycles.com/continental-race-28-700c-presta-valve-inner-...

Note: the liners are longer than the inner circumference of the tyre. I think we're supposed to snip them too length but I recon it's easier to overlap the liner. Whoop whoop regarding extra weight at overlap and tyre unbalance. Overlapping opposite the reflector should counter such good enough. If she shakes at high speed her knot might be too stirred up.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com.au%2F...

These are expensive yet great. LBS was cheaper than flea bay. Used tyres until 100s km past no tread. Very rarely punctures. Last puncture was with wheel that didn't have a liner. If liner was there the tube wouldn't have known the prick.
I don't know if I've done the correct thing but I put a 35mm liner into my latest 28mm tyre figuring it would absorb along wall a bit.
Easy as too use. Reusable.

23-28mm tube is a pretty decent size.

They would be suitable, yes. Personally, I would try and find one where your tyre size is more in the centre of the quoted range ie Your new tyres are 25 mm and those tubes are 20-25 mm but, as someone else said, 23-28 mm would be more ideal.

Probably not  a bad idea ordering a few tubes in the smaller size, yes. When you're googling, search for multi-pack, they can be a lot cheaper if you buy in bulk. This place is good.

+1 for GP4000s. 

Agree with most of the above.  I generally run Conti 4 Seasons in Winter and GP4000sii otherwise, and, as long as you change  tyres when they wear out they should be trouble-free.  Last year, to get rid of some old stock and as a  bit of experimentation,  I ran sets of Michelin and Vittoria G+ / Roubaix / Corsa tyres: whilst they are undoubtledly fast and well-suited to smooth European roads, I had more punctures and serious cuts that needed attending to than usual.  I've not tried the Conti Ultras, but was seriously tempted at the <£15 they are being offered at on EvansWiggleReaction.com

I'd deffo go for 25 or 28mm. Continental Ultrasport and Grand Prix are both very good if you don't want to spend top dollar. Grand Prix 4000 S II are as good as it gets if you want to push the boat out. Have a look here, it's an interesting read.

If using tubes, Tuffy tyre liners or similar Kevlar liners work really well.