Then, deliver your polished proposal. Save it in a PDF file or print it out, or both. The best delivery method for you depends on your relationship with the party who will receive your proposal. It's common to attach PDF files to email these days, but for your situation, it might be most impressive to hand_deliver a nicely printed and signed proposal.
Templates save you money: If you use a royalty_free template, it likely costs less than hiring someone to create a custom graphics package for you. You could easily spend hundreds (or possibly thousands) of pounds on a custom motion graphics opening, for example, whereas you can frequently purchase a royalty_free template for under £200. Of course, the royalty_free template isn't as unique as a totally custom template, but it definitely costs less, and you could always customize the royalty_free template to make it more unique for you.