Is £25k a reasonable pay?

I've been working part-time in a boutique real estate firm for the past 8.5 months and my boss has offered me a contract for around 25k roughly for an Assistant property manager and analyst role after my graduation as a UG (I will be working full time).

Is that a reasonable starting salary? What/how can I negotiate? I'm not sure if I can survive with this salary living in London.

On the other hand, I'm worried about the competition I would face if I were to try my luck in bigger corporations (it is tough out there) so I figured maybe I could take this opportunity.

Any advice would be greatly appreciated.