Hi Jodi,
This is the first post on the new forum layout!
The easiest option is to apply for a new VAT number under the Limited company name, and then apply to surrender your current VAT number. Its quite a straight forward process, and the forms are available on the HMC&E website for that.
As for the forms from Companies House, are these for registering the Limited company? If so, and I know you would expect me to say this, but comparing £20 to Companies House, around £15-£20 for a set of Mem&Arts from somewhere like Staples and then about £5-15 to have the forms notorised by a solicitior -- its easier to have a formation agent set your company up for you surely?