Thanks for your replies guys, really helpful.
Jimp, I appreciate the company names and I appreciate the expansion into the security/update side of things, thanks.
As far as CARP goes I'm not sure how I could utilize and granted I have not built a CARP setup before. Our setup will go;
Fiber in –> What appears to be a media converter (Provided by ISP), ethernet out --> Cisco Router (Provided by ISP) single ethernet out --> Our current/replacement pfsense firewall. I can whack a diagram together tomorrow if that makes it clearer but because the Cisco router (which acts transparently as far as I can imagine; we have the public IP presented to the WAN interface on our current firewall and only need to NAT on that existing firewall and nothing above. I don't know how they set it up I'm just making educated guesses. I'll ask the person that comes out to program the cisco router. We're with BT by the way unless anyone knows) only has a single ethernet port coming out of it I don't know what I could do in terms of failover from there apart from having a warm spare (with an interface on both for pfsync if that's how it works? I'll look though the wiki/docs/forums/book) and physically change the cable over in the case of a firewall outage?
I do also like the idea of the support being provided by people who are also the developers. It would also be nice to put some decent contributions in and fund new features. On which note I'm glad to see there's processing for credit cards, as much as I love pfSense I couldn't help feeling the uninformed I may have to pitch my choice to may not value a solution that could only process paypal, so I'm chuffed!
Anyone got any UK based companies they could suggest? I'll be doing the usual Google reccy too. It is likely however that I'll reutilise some soon to be old servers and build the box myself, all the servers are the same model which will make any possible replacements my easier.