Ok so i think ill get this lax, has 2 speeds, and im pretty sure with my little space should be more then adequate on low speed for the time been.
http://m.ebay.co.uk/itm/SALE-XFLO100S-in-line-Mixed-Flow-4-Hydroponics-Bathroom-Extractor-Fan-UK-PLUG-/390620127959?nav=SEARCH