Bless BGG he tries: SSM7 is how you measure (for costing purposes) not actual prices, I have checked out Spons (commercial price book) and for bricks laid on edge in a herring bone pattern expect £49.68 m2 if you lay the bricks on face then expect 30.64m2. These rates are for commercial so you may pay a bit more for domestic.
Things to consider:
Yes you need planning permission for non-porous finishes this is due to surface water being diverted into local drains & possibly exceeding the capacity of the grey water network.
Depending on the aesthetic you are after reclaimed bricks can be a cheap option (but not red ones as they are more expensive)
If you plan on having spoil heaps / plant / skips in the pavement you technically need permission from your highways office
Doing it your self may seem cheap but consider plant hire costs, transport costs, sanity costs, extended duration of works, where do you park your cars in the meantime?
If you are worried about weeds use a commercial strength herbicide on your excavated plot.
Considering current economic conditions many small companies are struggling, do not pay upfront for anything.
Check your local area for any “groundworkers” they are the firms that do the work commercially but if they are quiet (most likely) they may consider your project.
Agree a lump sum figure not re-measurable.
Check all drains, kerbs and other details prior to signing off / paying for the work.
On domestic work the use of your welfare facilities (toilet) is expected but to save your carpets put down cardboard on the route.