Wow, thanks for all your responses so far!
Managed to jump start it before, took it for a run, but once i stopped and turned ignition off it wouldnt start again.
Jump started again and took it to local garage, guy checked the battery and said it was dead. Then turned ignition off, and it started again, although reluctantly. He then suggested ignition switch...
It drove home fine after going through the puddle (at least a 15 min motorway journey), and it was quite deep.
My parents suggested hitting starter motor, but my dad couldnt find it, and i dont know what im looking for to be honest.
Lights are all operational (headlights and dashboard lights). Just tried it again just now, about 45 mins after taking to and from the garage and it started fine, left it running for a few mins. Thanks for everyones help btw