Going to be very hard landing something acceptable for making youtube videos for that money. I mean, just have a listen to £150 headset mic tests on youtube and think who's going to want to watch your vids sounding nasal/windy.
Have a look at these parts for a top-notch sounding mic set-up and see if they tempt you:
Behringer UMC22 Audio Interface - £32
Behringer XM8500 Ultravoice Dynamic Cardioid Vocal Microphone - £17.50
InnoGear Heavy Duty Microphone Stand with Mic Microphone Windscreen and Dual Layered Mic Pop Filter - £14.99
Stagg SMC1 1 Metre Microphone Cable XLR-m to XLR-f - £3.70
The UMC22 is currently cheaper as well as better than the UM2.
As for headphones, and if you want to keep to a £100 budget, there's the Superlux HD668B for around £30.