No installer worth his salt would put an aerial INSIDE a roof unless you live right next to the transmitter. You'll lose an enormous amount of signal thru the bricks, tiles or whatever. An aerial booster will not make up for the loss. It will simply amplify the noise as well as the signal. TVs are designed to work with very small signal levels but what they need is a good signal to noise ratio. This can only be achieved by having a good aerial in a good location. The only use for an aerial booster is to overcome signal loss thru a long downlead - and for this it must be at the aerial end.
£200 - You were ripped off mate!
There's some useful information in this thread:
http://www.cableforum.co.uk/board/26...view-help.html
In particular, you might check out the terrain mapping from your nearest transmitter to your house. You'll be able to see if the height of the aerial will make a big difference to the signal.