Will give it ago, going to order a big tube of aquarium silicon from ebay.
I popped into Wickes today but all their silicone says not for aquarium use.
I also popped into a local aquarium shop, their tubes of silicone were £9 each so I left them! Not in that much of a rush.
Will gather the next few bits over the next couple of weeks
Silicone for the repair
100w heater
Light Bulb
API Master Test Kit
Just out of interest - I was looking around the fish in the shop, and they seemed quite cheap - lots were 10 for £7 or 5 for £4 etc which seemed alright to me, but I must have counted over 20 dead fish in the tanks - is this normal or is that a shop to avoid for the fish?