They do (like so many others) have a fair usage policy, for the FTTC product set at 60GB a month. Traffic shaping only kicks in if you exceed that and not for normal web activities like email, web browsing etc. However strictly speaking, their fair usage policy doesn't actually set any limits for the upto 40Mbps product, it only lists the up to 8Mbps product (though I'm sure the same policy is probably applied).
They call it their BroadbandMax which kind of is their top speed pack for either ADSL2+ or FTTC which share the same package name and pricing.
40Mbps down, 10Mbps up, unlimited off peak usage, free IP addresses and £24.99 pm.
Any traffic shaping they may do if you exceed the limit is restricted to 8am to midnight monday to friday and off peak is unlimited.
They have a completely uncapped/unshapped product (their "Office" product) which is listed at £45 when you order but doesn't state if that includes VAT.
I've been tracking my usage on their control panel, it's a bit rudimentary, but it does the job. So far I've used just under 4GB peak downloads in a week and 6GB peak uploads (I'm using Carbonite for online backups which accounts for all of this upload volume).
I'm going to monitor the service closely, and if I have to I'll upgrade to a higher tier, but at £25 a month it's excellent value, and it's not BT.
I'm going to drop them a line and get some further clarrification on their policies though as the online documentation clearly hasn't been updated since launcing the fibre product and we all could do with having a bit more info I think.