What accounting software would you recommend for first-time entrepreneurs? Are their any open-source solutions that can be self hosted that integrate with existing solutions?

I am just starting my journey into entrepreneurship, and have yet to choose a bank or accounting software, and would appreciate guidance. I am based in the UK, and will only be conducting business in the UK to start off with.

Not OP but there are a few open source options. GNU cash is friendlier for beginners due to the GUI. I like plain text accounting, specifically beancount.

As far as integrations, GNU cash lets you import from various formats like quicken while beancount has lots of plugins from the community like importers for various banks. I don’t believe either offer invoicing but you could integrate it yourself or just manually record.

IMO, the hardest part of keeping your own books is learning double entry accounting.

Starling Bank as the bank, and FreeAgent as the accounting software - it'll handle personal tax (self-assessment), corporation tax, VAT, and payroll. If you need an accountancy practice, I very much recommend Maslins - they'll provide FreeAgent access in that case as part of their fee.