I've used them both.
They both have history in the same company, but split at one point. They also have a series of shops, they are the largest chain for pop culture and comics in the UK.
They've also always come through totally fine for me. If books aren't in stock, I'm pretty sure it says so on the product page (I bought the last copy of something from one of them once, and it changed to an 'Out Of Stock' notice straight away).
Looks like they wait until an order is ready and packaged to provide overseas shipping costs, I guess to make it accurate.
My experience with them is the same as rynprc.
I can vouch for them wholeheartedly.
You can order monthly comics through FP.com, which is not possible with FP.co.uk that is more specialized in collected edition or GN for the comics section of their shop.
With FP uk, when an international order is ready to dispatch, they charge you for the books (if you have used a credit card) and send you an email with the accurate shipping costs to know if they are acceptable to you. By default, if you don't respond within a week the order is cancelled. If you decide to cancel the order you will be of course refund automatically. To give you an estimate, from UK to France it will cost around £8 for a library edition like Buffy, £10 for an Artist Edition style book, and £14 for both. Notice that to France they use a 2 to 3 days DHL delivery with tracking number. And they package very well (it is why they are currently my preferred choice).
latest! Hellblazer vol10 is missing from the pic cause I'm reading it right now and left it on the bed :P
I'm up to vol 7 now with Prince Valiant sadly only read 2 volumes so far because of my backlog.
Aaaand my Gundam line is complete!!!
FP.co.uk do actually do monthly subscriptions too;
http://www.forbidden-planet.co.uk
The changing of the spines for Buffy is messing with my OCD lol. How is the Nemo Trilogy?