firstly never take offers/quotes from “passing tradesmen”. 9 times out of 10 they will rip you off.
i do accounts ffor a couple of property companies and theyve had trees removed or trimmed including some very large conifers and they havent paid anywhere near your “quotes”.
also before you have any work done check with the council it could be subject to a tree preservation order which will effect what you can and cant do.