Phew! Making arrangements for a campus visit isn't as cozy as I had thought!

Can somebody help me out with these queries?
>> I'm looking for super quick processing of my UK visa from India. Is hiring an agent (Thomas Cook maybe?) a good idea?
>> Is travel insurance a must in the UK? How to go about eets?
>> what's the best way to carry local currency? Get myself some Thomas Cook/AMEX travelers cheques or do I purchase some GBP forex from India itself? Any other ideas?
>> Both schools (Ox/bridge) are taking time to respond to my request for campus visit. I'm guessing it's because of the peak application season. If I send them a gentle reminder to take a look at my case, will it be perceived negatively by the schools? [I'm really hoping for an answer from them soon, because I can't go forward with my visa processing without a letter of invitation from them

]
Cheers!