singlespeed question (sorry)advice please

need a second bike just to ride round with the kids and thinking it might be worth getting a singlespeed (cheap)then I could use it for a bit of local off roading aswell.Looking on the internet I can pick up a diamondback for £250 it’s a mojito 29er or should I stick to a 26er as all my tyres/tubes are 26 if so any recomendations? Looks like I can get a GT peace for about £300 don’t want to spend that much really but it looks good.
Thoughts please

Think I’ve heard people say a 26″ tube will ‘stretch’ to a 29″ wheel, but I have just got up after a few Stalla’s last night!!

buying extra tubes is no hassle really.i wanted a cheap single speed fully rigid.so ive heard that 29 inch wheels roll over ruff terrain much easier which makes sense if your riding a fully rigid bike.i didnt want to spend loads of money because i dont know if it will suit me.so only the week before last i bought a 29inch gt peace off ebay.it is second hand but has hardly been riden at all.with carbon bars and hydrolic disk brakes. i won the bid at 230 and ive only riden it twice but so far im loving it.and it stops me from wimping out with those grany gears 👿

Have you seen this one? GT Peace 29er

The GT is a slightly more Singlespeedy singlespeed as it has no cable runs for gears, but the Diamondback might be better if you fancy putting gears on it at any point because it has cable runs, a mech hanger and a spacer kit on a “normal” cassette.

bugger I need a large

theres a large gt peace 9er on ebay now 2 hours left.26inch though.a black one.dont know if youve seen it.im 5ft 10 ive got a large cove handjob but the medium peace 9er fits me as good as the cove

You probably already know but Winstanleys have the 26′ one for £299

does anyone rate the gt peace?