We specialize in analytic jobs in US, but are also very interested in further growing in Europe. We also have our network, see www.analyticbridge.com, where we (and some partners) post analytical jobs.
In addition it's well worth getting your site listed on the UK job posting services (www.Broadbean.co.uk, www.Jobmate.co.uk, www.PostingPal.com and www.Conkers.net). It's does not usually cost anything to get listed on a UK posting service, but you might need to do a bit of development to get your systems ready to receive content from these sources.
If your serious about a UK presence then participation in NORAS (www.noras.co.uk) can bring a reasonable level of publicity, but this will involve taking part in the yearly survey and having your traffic levels audited.
As Steven R mentions, your advertising goals will influence how relevant these sites are, but they might at least provide a starting place.
The UK IT world unfortunately has, in my opinion, few directory sites that are of worth. There are good options for job boards looking to gain audience or clients though. What are your advertising aims - are you looking reaching out to businesses intent on posting jobs or candidate growth?
I need recruiters aware that they can post jobs for free now even though they are likely to have few jobs at present. Other than e-mailing them directly about the site are there any other avenues to take. The arena we intend to target is yet to flourish and recruitment needs are low in the UK at present.
My advertising aim at the is to draw up a plan in preperation to begin an emergence when there exsists more of a market.
If I'm following this correctly your looking at a fairly niche specialist within the IT/web designer world.
If your looking to reach out to direct employers I'd recommend you consider advertising options with sites like c|net and computer weekly. For tech recruiters the blogosphere is the probably the best route, particularly for smaller to meduim sized recruiters (recruitingblogs, recruiting.com, etc). You obviously also have the option of the local newspapers (I see your at hotonline so you'll know the options via TM).
When you move on to candidates you've got the option of the vertical search engines like Indeed, JumpToJobs, AllTheTopBananas and WorkHound (all have a uk focus/site). However, if the niche is very specialist I'd recommend you look into new media such as podcast, blogs etc - it obviously depending your budget and specific niche but broadcasters like TWiT (twit.tv) and Revision3 are becoming big players in the tech world, with good audiences. These mediums might also be useful for reaching direct employers.