St Albans City and District Council states the conservation area rule in its own words: "If you live within a Conservation Area and wish to cut down, uproot or prune a tree you must give the Council six weeks' written notice before carrying out any work." On its Tree Preservation Orders page it adds that determining an application for works to TPO trees can take the council up to eight weeks. The council puts the maximum fine for wilful destruction of an order or conservation area tree at 20,000 pounds per tree, and wilful damage at 2,500 pounds per tree. On the national side, gov.uk separates destructive offences from other contraventions and says penalties can run to an unlimited fine. Which figure applies turns on the offence and on the court. The district has 19 conservation areas, St Albans and Harpenden among them.
The council also runs a fast track service, which it describes as a "Fast-track service for applications relating to TPO trees and Conservation Area notices", with a decision "by the end of the 4th week after validation unless they are called in for a Planning Committee". It states that the service exists only for applications made via the Planning Portal, and that the request must be submitted within 5 working days after the acknowledgement email.
Nationally, gov.uk describes the requirement for "people to notify the local planning authority, using a section 211 notice, 6 weeks before carrying out certain work on such trees, unless an exception applies", and says the work may go ahead sooner where the authority gives consent. gov.uk also states that consent "is needed for carrying out work on diseased and/or dying trees unless some other exemption applies", so a dying or diseased tree is not automatically exempt. Dying on its own does not establish a statutory exemption. We would put the council's page and the national guidance side by side and show which control applies to the work. A tree preservation order applies to the trees named on that order.
On felling, the Forestry Commission service states that a licence is not required for trees in private gardens, orchards, churchyards, or public open spaces like some parks, and that up to 5 cubic metres can be cut from a property in a calendar quarter without one, of which no more than 2 may be sold.
Two national wildlife protections sit beside the tree controls. gov.uk states that "All bat species, their breeding sites and resting places are fully protected by law", with damage to a breeding or resting place among the offences it lists. Its wild birds page adds that taking, damaging or destroying a nest in use or being built is against the law. Both would sit on the rules page with their links.
We would explain how you check the conservation area boundary, any tree preservation order and the proposed work before confirming whether a section 211 notice or consent is needed.