This might end up lengthy so I apologise in advance - feel free to skip past it!
Depending on the department and grade, there is scope to be doing advisory, forecasting etc in practice. The pure accounts/tax return preparation roles are really at junior grade - once you qualify you should be reviewing the work others have prepared and also doing broader work.
Industry's 'boring' flipside is month end procedures, every month the same thing the same pressure. Whereas practice you get to work with lots of different businesses in different sectors and have different routines and pressure points each month. (Some people don't like that, I do.)
Most people train in practice and either move to industry when newly qualified or at manager level. Progression is slower, less structured in industry - and also more competitive. But it is possible to train in industry.
You say you're late 40s. So 2 year AAT apprenticeship and then 3 year training contract for chartered status (ACA/ACCA/CA). So 5 years minimum to be fully qualified. Have you checked whether you meet the entry requirements for direct entry for an ACA/ACCA/CA training contract instead (I should think you would)? Your day-to-day role and on-the-job training would basically be the same either way.
In practice once newly qualified the position right now is that most places would bump you into an assistant manager role (or equivalent) at that point, with a year or two to progress to manager.
As assistant manager you'd have a portfolio of clients you were responsible for to ensure their accounts or tax or both were all completed on time (depending on whether you were in a specialist department or a general practice role). You'd have to deal with managing the time budgets for the work and billing, client relationship management, reviewing junior work, training and supervising juniors.
What do I personally like or dislike as an accountant in practice?
Cons
Timesheets are annoying, time-based billing can be dysfunctional and frustrating. However you get used to it (it helps if you work at a practice with a more sane approach rather than one that expects you to work all hours to meet billing targets).
There are recruitment and retention issues in the sector so sometimes we are under much more pressure than I'd like as we are either understaffed or the fee quote is too low for how long it's going to take us.
Sometimes it is boring. Keeping up with technical changes can get draining sometimes when rules and legislation are continually changing.
Deadline pressures.
People turning up at the last minute and expecting me to work magic.
Life in practice is predominantly a very young crowd so sometimes it makes me feel ancient.
Pros
I'm experienced enough and senior enough that I'm trusted and I have flexibility to manage my calendar. I have control of my days, I'm not being spoonfed tasks or micromanaged.
Outside of audit, from senior associate level (say 3 years) you're already mostly trusted to manage your own time. Audit is more controlling at junior and senior because you're booked out on jobs and will be sent to a client site for the week. In accounts or tax roles, you'll have a set of clients and you'll know their deadlines so it's up to you to plan your days and weeks to deliver.
The technical side is interesting, especially tax which changes all the time and has an impact on wider society.
I work in a medium sized practice so I have a team of people around me who I can discuss technical issues with. And they're a good team of people who I enjoy working with.
Pay and work/life balance meet my needs.
Being able to mentor and train more junior staff - pretty much from your second year you should start having opportunities to do this. It's rewarding to support people to fulfil their goals.
Clear structure of roles, progression, rules, requirements, training.
I like being able to help clients - whether that's taking away the stress of dealing with HMRC, or helping them figure out how to turn their loss-making business into a profit-making business, or helping someone with a problem that's been giving them sleepless nights.
I like puzzles.
I also like stability and structure. My role in my practice with my portfolio provides that. I know my clients, I know their needs and their business cycles, I know roughly when in the year I'll be under pressure or have breathing space. The general pattern of the year tends to be similar but even on the same client each year will bring new figures, new questions, new problems to solve.
I enjoy getting to know my clients' stories. I have clients from a wide variety of sectors and backgrounds with varied setups. I find it interesting learning what makes them tick, how they operate, what their pressures are, what legislation affects them, how they look after their staff, how they develop their products, what costs they incur, etc. It compensates for the routine repetitive parts of the job.