Much advice needed for an 8' x 4' cnc router project / and vacuum table

Hi guys,
I'm James, I own a small company and looking to purchase/build a cnc router.
We are on a budget, but do have one to work with.
This machine has been something I've always dreamt of having, so really want to get the right machine and some unbais advice if I may?

We would be cutting 8' x 4' plywood in thickness of 6.5mm and 9mm (occasionally 18mm in small amounts), into a number of sections. Some boards may only be cut into 2/3 pieces, however others may have 20 panels cutout of it.
We will also want to drill 5mm holes ready for rivet fixings during construction.

So the main machine questions I have are:
- Can a 5mm wide router bit be used to cut through the plywood as well as for drilling the holes? So that we don't have the spend time changing bits mid run..
- For a budget of circa £5500 ex vat what would you recommend? (cnc machine)

The vacuum table -
After hours of reading and searching online the best option seems to be a plenum system with spoil board.
This way we could build our own MDF table with 6-8 vacuum 'hot spots', using a vacuum connected to a PVC piping and valve system under the table. Allowing selection of which spots are applied.
I have drawn this idea from a guide on Shopbot Wiki 'vac hold down system'.

My budget is about £1000 for the vacuum/s..
- What spec of vacuum system do you think would be strong enough? Baring in mind we are going to be cutting through the plywood sheets and exposing small amounts of the spoil board.

Any advice will be really appreciated, cutting plywood by hand is just taking too long! :smile:

Thank you!
James