I am not speaking from experience so take what I say with a pinch of salt.
You can probably work on improving your research proposal as it will be the main way of assessing your funding application. Do a small literature review, clearly identify your research gap and have a clear methodology.
I would also ask your potential supervisor about potential funding avenues and investigate your best options so that you can apply early and often. Different funding bodies have different requirements or focus, so you want to be prepared.
You should consider other universities as well. I understand you have been accepted to one university but some universities have more internal money than others and you don't want to get stuck at an underfunded university. The results from REF should be coming out this year and that might start a deluge of funding opportunities, as some universities have held off internal funding until it is over.
If you have the time, you could start working on small side projects, maybe in conjunction with your supervisor and get some raw data or a small paper. Though it isn't necessary and is very time consuming with a small chance of paying off
Hopefully other people can give you more advice.