1. Buying off bittylicious. PROS - It works and you can pay by bank transfer in £. CONS - You have to start off small, and its premium price (between 4$ and 8$ I've found).
You could try
Bitstamp, although exchanges are nearly snowed over right now.
2. Set up wallet on greenaddress. PROS - Easy and free. CONS - Costs to move bitcoin around. Buy off bittylicious and stick here.
Yep, greenaddress is pretty solid. You could try a software wallet like
Electrum, hardware wallet like
TREZOR or both together, and this would be pretty secure/user-friendly.
4. Trade and buy alt coins on bitrex.
Good choice. You've clearly done your research on exchanges and wallets (avoiding blockchain.info and Poloniex).
Not yet tried withdrawing back into real pounds. Be interested to hear from anyone in the UK.
Unless you're a trader, just spend. Don't think of it as "real money" and "Bitcoin". Fiat money is not backed by anything anyway.