Registering off road stuff for on road use?

I wanna buy a motocross bike, for some off road fun, but its gonna be much more useful if its a road bike, as i can use it in the winter to go to work, and stuff when the sv is having work etc.

so been looking at stuff, and i'm wondering if a bargain pops up and its off road use only, what does it have to have done to it normally to be road registered? is it too much like hard work, or is it a case of giving it a headlight and an mot and stuff? do you have to have indicators, coz i'm sure i've seen old bikes and that without them, as long as you do arm singles?

and what about daytime mots? i'm sure ive seen race bikes advertised for sale, with no headlights, or indicators, just a brake light. coz that would suit me, coz i'd only use it in the day anyway.

any information would be great, as you can see i'm a little lost by the whole thing

mods, feel free to delete this, i didn't search properly and think i've got the answer now, sorry