In reply to LastBoyScout:
I'll offer some advice for what it's worth, I fit doors and windows for a living. Much of the advice on here about second hand doors is good but it's a good idea to know what you're buying. I wouldn't buy new from a website. Don't buy from Wickes or B&Q.
Window companies do have good quality removals leaning up next to skips, I've refitted a few doors myself for less well off customers to help them out.
I don't know what you keep in your garage but if you have items of value in there then I'd stay away from PVC as the panels can be kicked in quite easily. Composite is expensive but many factories have mis measured doors in what we often call the 'graveyard' and will let them go cheap. Ebay is an option if you can find something local.
The lock cylinder where you put the key MUST be a 3 star anti snap lock or the break in time will be around 30 seconds.
I'm based up north but if you need any info then feel free to contact me directly.
Post edited at 10:04