Elm is a temperate climate plant. Should be outside.

Hi -- several things to say:
1. be careful about well-meant but incorrect advice.
2. find a local bonsai club and join it.
3. read bonsai books -- I especially recommend authors Paul Lesniewicz, Colin Lewis & Stan Gustafson for beginners; also look for anything with pictures (inspiration).
4. bonsai seems to be a trial & error thing -- learn by doing. Sorry, but some trees die. Don't be discouraged.
5. your tree: I like Chinese elm for a beginner because it grows fast (makes you give it attention) and gives quick satisfaction. It is deciduous & while I don't know weather in England, here in Connecticut, US, it is marginally winter hardy (ie: winter in an unheated garage or basement unless you know).
6. your tree: soil does not look like usual bonsai soil & may be wet. Suggest you repot (with root trim if necessary) using traditional soil -- ask at the club, else find a mail order place -- should be gritty stuff. (Is a bit expensive.) I water daily till it runs out bottom. (My trees live outside all year; only some come inside Dec to March).
7. your tree: nice if common trunk shape but way too little foliage -- let it fill in: Usually, let branches grow to 6 or 8 leaves (more at first) then cut back to 2 -- always use clean, sharp tools. In your case, maybe let them grow longer, to thicken, then trim short to make side branches.
8. your tree long view: classic triangle shape is started -- I suggest trim to that outline. Some straight branches there are candidates for wiring. Good down-bent branch & back branch with clear front to show off trunk. Top has potential, too.
9. enjoy!

Thank you very much for taking the time to help me out bononnie. You have been more than helpful. Take care :)