Yes - I believe the VHF regs are now in force - however you can get hold of/ borrow/ hire/ some portable kit fairly economically I have heard - contact St Pancras Cruising Club - as per website below for more info on this.
For more info on navigating on the tidal Thames try this: http://www.stpancrascc.co.uk/ and click the 'Cruising Guides' link on the left side Good luck Tony
