I tried a few out locally last week to try and see what different mechanical switches felt like. I didn't like the feel of the cherry MX red ones, there weren't any brown or blue switches to try. I would perhaps see if you can try some out nearby as whilst the selection wasn't that great I found it better than nothing.
In the end I ordered a Ducky One 2 full size board with blue cherry switches (I'm still waiting for it to arrive due to weekend and New Year) though it is over your budget. They do have some under £100 that don't have any lights and are TKL (Ten Key less) without a numpad. Other colours and also types of mechanical switches are available.
The full sized ones including a number pad (with no lights) are just over your £100 budget. Again various colours and types of mech switches are available.
I went with ducky as these ones have PBT double shot key caps (which are better quality than ABS ones which wear out quicker and go shiny from wear). The bottom row keys are all standard sized making it easier to customise with various keycap sets if you want to change key colours. The cable is removable, not that big a deal as I've never worn one out but nice to have. The font on the keys look nice (imo), whilst the Corsair board font for example looked horrific. Ducky also has the extra keys that I use the most on my current board, vol up and down, mute and a shortcut to load calculator. Note that you only get these on the full sized board as they are above the numpad.
You can also get the TKL shorter boards with single colour backlit keys for just over £100. Some examples all with the clicky blue switches (you might need to look up or ask about the different types of switches and what colour switches mean what if you don't already know, I did the same last week as I didn't know the difference). Some boards are out of stock at the moment, think a restock is due in Jan some time, you'd need to ask OCUK to find out.
Lastly there is the new Ducky mini for £110 which doesn't have a row of F1~F12 keys, arrow keys, or numpad etc which apparently are popular among gamers as it gives more room to move the mouse. I use a lot of those keys quite a bit though so it's not for me. You have to use the Fn key in combination to convert another standard key to duplicate those functions, for example Fn+1 = F1. I find this a right pain on my laptop but your milage may vary. Hope this helps, I'm no expert but just happened to do some research last week. Any more questions fire away and I'll see if I can answer them.
My basket at Overclockers UK:
