Hi, Im in a similar situation and this is what Ive found in NZ
The Camera and Recording devices need to be matched, so you may find a Kit more useful with the addition of the PTZ cam. POE or wireless (power over Ethenet cable to recording box or internet if avail- gives you cell photo pictures... good for Biz and reporting to police)
Min of 1080P Full Res on Cams and recorder/playback otherwise the lower resolution (720p) is useless to identify for prosecution. also 2MP pixel seems pretty good base to start from.
Checkout retailers in UK that have installers as well (if possible) or chat with those that install to get some clues what you might be facing. So much low Quality stuff on market by brand, you will get familiar quickly by what they don't tell you about the cameras!
Just my 5 cents worth, All the best.