I pay a fixed amount to Peninsula monthly, which covers all legal advice and documentation for my 3 businesses, all of which employ. So my amount will be greatly different to yours. However, because I signed up for a 5 year period, my fee will not increase, regardless of how my companies grow and how many employees I take on. If I sign for a further 5 years, my fee stays the same. It proved to be quite expensive for one employee, but now I have grown on all fronts, it is cheap as chips and will continue to get relatively cheaper the more I grow. I'd recommend you contact them as they put on free seminars which are obvious events to drum up business. It's an excellent way to see if they are for you though. For me, they have been 5* all the way.
I'd say that Susan Dean's builder friend perhaps cocked up very early on and is not comparable to your situation. My lads certainly don't have their own legal team, so I doubt they'd challenge me about things. They have their copy of an employee handbook given them on arrival. It's over 40 pages long and covers everything. There is no ambiguity. I also keep a copy in the van so they have it for their reference whilst they are out and about and something crops up. We all know exactly where we stand with each other and what we are all legally entitied to. There is very little fuss.