Does IOE have funding to help provide open access in subscription based journals, if I were to publish there?
That's wonderful that you want to publish an article from your dissertation and make it available on open access. You will have plenty of options for making this article open access without paying a fee. Do you have a journal in mind in which you would like to publish? If so, it's worth checking the publisher's and journal's policies on making the article available as open access: http://www.sherpa.ac.uk/romeo/. You can thn ensure you choose a journal which has a permissive policy. You might also want to consider trying to retain your copyright in your article rather than assigning it to the publisher (see http://www.sparc.arl.org/resources/authors/addendum for advice to authors abuot your rights).
The SHERPA Romeo service mentioned above lists journals and publishers which do permit free open access (even in subscription journals) - and these are colour coded green in the website. There are links through to each journal/publisher's copyright page and you should always check the small print.
Open access comes in two flavours:
Green - you may add the article on an institutional repository (eg of your university if you are still affiliated with one) free of charge, where the publisher and journal permit this. If you are unaffilliated, there is a repository where you can make your article open access (again free of charge providing that the journal you have chosen does permit this). The repository for unaffiliated researchers is http://opendepot.org/.
Gold - this may be the open access that you're thinking of, although it's sometimes referred to as a hybrid model (open access articles within subscription journals). This is where you would pay a fee to make your article open access on the publisher's website. There are some funds available for this kind of open access available to current academic and research staff and to current UCL research students. There is a guidance page here on open access: http://www.ucl.ac.uk/library/open-access/basics. As you specifically mentioned publishing in a subscription journal I haven't mentioned open access publishing in a fully open access journal, which is considered the true Gold Open Access route. Some of these are peer reviewed and may be worth considering. Fees to publish in them may be lower or there may be no fees at all. The well respected DOAJ service lists all the main open access journals: http://doaj.org/