I'm an HR professional, to try and briefly answer your questions, yes there are lots of jobs (although it varies depending on where in the country you are, industry and specialism) - pay is good at the higher levels (although I wouldn't say very highly paid, not like IT, banking, law etc., but a good level of pay commensurate with professional qualifications), but as pp says it may take you a while to get there. This is a good guide to salaries, go to p152 for the HR bit.
The recognised professional qualification/accreditation for HR is via the CIPD and if you want to progress in HR you will likely need to get some qualifications, most people either study their way through the levels part-time whilst working or do a full time masters degree with CIPD accreditation. If you can cope with reduced pay for a while a preferable option is probably to try and find an entry level role (as an HR administrator, L&D Officer or similar) and study alongside that, as IMO graduates with the masters degree but no previous experience working in HR can then struggle to get a graduate level job, there are a lot of competition for those roles and employers prefer people with existing experience in the field as it were (you do have the advantage of solid work experience of course so you will have a bit of a head start there). If you are lucky you may find an employer prepared to sponsor you/part-fund your CIPD qualifications which would be ideal as the masters is quite pricey to self-fund... Have a look at the CIPD website which explains all the membership and study options.
Day to day, if you wanted to specialise in learning and organisational development (as opposed to being an HR generalist or one of the other specialisms like recruitment, employee relations, change management), in an entry level role you could probably expect a lot of admin, room/venue bookings, booking people onto courses, printing or managing materials for the courses/events, setting up and minuting meetings, inputting/extracting data from spreadsheets/databases and quite a bit of customer service e.g. answering phone calls and emails from staff and training providers. Most organisations also have some kind of e-learning portal/website these days so you would probably have some input into running/managing that as well.
As you progress you can become more involved in the actual design and delivery of the courses, set up and management of L&D schemes like leadership development programmes, apprenticeships, graduate schemes, corporate induction programmes etc. But on a day to day basis, unless you want to be a full time trainer/facilitator (which is fun but can have a bit of a ceiling on it in terms of career progression!), it's still quite a bit of admin and 'management work', emails, meetings, managing data and budgets (making the case to be given money to run the courses/schemes you want to mainly) etc.
Any more questions, do ask!