If you plan on changing the main Breaker (fuse?) for the whole circuit. Does that curcuit just supply your room or is it like a bedroom/office/downstairs/etc ring? Either way get an electrician in, it'll cost you more short term but then re-building the house having burnt it down with an electrical fire in the walls will cost more. Generally speaking what ever the circuit is rated for 20A 15A whatever, will be lower than what the circuit can handle but the more it handles to higher the chance of catastrophic failure...