The 100s arnt bad but they could do with a 0.02% pitch rise value rather than the 0.1% for more accurate mixing. Also they havnt got many features but that doesnt bother me tbh. The cdj200s might be a good shot at though as they have the lower pitch rise value and more features with looping. As for the mixer there are a lot of midi mixers about at different prices.
The best dj equipment shops in my opinion are:
DJ Store | DJ Equipment | CD Decks USB Turntable Mixers MP3 DJ Equipment in the UK DJ Equipment, Decks, Mixers, Headphones, Buy DJ Equipment - decks.co.uk
I always use djstore and they offer a brilliant service.
Try to stick to pioneer cdjs though if your playing in bars etc!
hope this helps a bit