Is there software I should be buying if so which is the best and
reasonably priced i.e. under £100 should I pay for someone to do it
for me on a monthly basis?  is there a free service anywhere? 
help...!

You want to be very careful about this.

There are people offering 'Web site promotion' services, some are
ridiculously expensive.

However a lot of the so called 'promotion' is really simply using
dirty tricks to try to fool the search engine rankings.

The people behind the search engines do not like this at all, nor do
they like people repeatedly submitting/re-submitting the same page.
So called 'promotion' can actually lead to your site being blacklisted.

It might be an idea to have a look at the News Group: 
alt.internet.search-engines

I'm also a bit dubious about specifying UK search engines only.
However you might be working in a very specialist field.