Database Website

The website I need to setup is from an existing and accruing Excel Database. Customers will buy credits to view x number of entries. Probably need something like Worldpay and PayPal payment options.
Obviously Excel will need converting to usable database on the site where customers can search for a name etc and if they wish to look at the entry click on it and their credits are then deducted. Ideally the final entry I would like as a PDF that can then be saved to their PC!
If possible I would like to be able to add new entries myself if conversion from Excel can be automated somehow?
I would also need someone who can iron out any problems that may occur so a regular webmaster will be needed to deal with any issues.
Obviously security is very important so as the information cannot be hacked. The launch date for the site is around August 2014. I would like to start the development later this year.
I hope to have 300,000 names to start with for the launch of the site and add on a monthly or bi monthly basis.
The server will have to be based in the UK.

I hope I have explained this clearly. I have built websites myself but this is rather more than I can cope with and not sure what is involved and costings. Apologies for that. I am attaching an Excel sheet with a couple of examples of what is to be dealt with.
Thank you