HMRC publishes some free bulletins containing first-hand updates. Of particular interest is the HMRC Agent Update with guidance and news for tax agents and advisers. There is also the HMRC Employer Bulletin with up to date information on payroll topics for employers and agents. You can subscribe to these online for free.
In addition, there some paid source of high quality relevant information, updates and commentary such as Ross Martin (on-line only; accepts annual or monthly payments) and Tax Insider (only annual subscriptions; on-line materials as well as printed newsletters, reports and books).
All Q & A's and other resources on this website are, of course, available for free and questions are typically answered promptly by professional, qualified accountants and supplemented with valuable practical information the wider accounting practitioner community in the UK.
UPDATE: We have now also published an extensive curated list of UK accounting and bookkeeping forums, some of which you might find very useful.