I posted yesterday agreeing with the suggestions that you do some work experience OP and I see you have commented since then that you have had some exposure to legal work so you are aware what it entails. To be honest, there are plenty of fairly interesting areas of work within the profession - my issue with law as a career is not with the work per se, but with the culture of law firms and the tedious processes involved in billing and time recording.
Having worked at a range of firms (I trained at a large regional - top 30 - firm and stayed for a while after qualification, then moved to a magic circle firm for a couple of years, then to another large regional and then to a small firm) I think it is actually easier to work in a magic circle (or other top tier city) firm than in any other, as billing is so much less of an issue. You put your time down, it gets billed, the client pays - simple. Also, you are likely to work on fewer things at once (for the most part - big transactions, for example, rather than 100 different people's wills/divorces/PI claims) and so it's less of a faff to record the time. Yes, there are longer hours - but the people around you would be the sharpest and the best at what they do, and the resources in terms of facilities, training and admin support are fantastic. The difference between magic circle/top city firm and large regional is enormous. Once you step down from the top tier firms, it gets much more difficult. My personal impression from the firms I worked at was that the magic circle firm wants you to do the work to the highest possible standard - they know they'll get paid at the end of it. The smaller firm (I include the large regionals I worked at in this sweeping generalisation, although there are certainly some very highly regarded large regionals that this may not apply to) wants you to bring in the most money.
Make no mistake that a private practice law firm would be a major culture shock for someone who has been used to the civil service - certainly, it has been a major adjustment for me to move in the other direction! Unless you go to a top tier firm, your main focus at work in a law firm will not be law, it will be money. It's all about the money. I think you need to do some work experience, not to find out what it's like to draft a contract or review a sale and purchase agreement - but to see what the culture of a law firm is like, and if you would want to spend your future career in that environment.
I think your comments regarding not liking being bossed about by a 28 year old suggest that you would also find it difficult to go back to the beginning. You would be at the bottom of the heap as a trainee - can you stomach that?
Whilst it is true that there are some flexible/in-house/part time options for solicitors, it would be a long time before you would get to the stage where they would open up for you. If you were able to get into the GLS, I agree with other posters that it would be a fantastic route. I would have loved to move into the GLS but sadly there's no presence in my location and I would have had to commute a long way (if I could even have got a job, which seems unlikely given that they're rare!!!) Legal work is great - the legal workplace is not (IMVHO).
In terms of other options, have you looked at other career routes in the civil service? I am on a graduate scheme which will lead me to do quasi-legal type work but in a flexible working environment with no chargeable hours. Might that be of interest to you?