How much time you spend is really up to you - training is flexible and can fit around your life. Most roles will ask you to aim for 27 days a year - and your weekly training session at your unit will count towards this. If you complete 27 days and pass the Military Annual Training Tests you'll qualify for a tax-free bonus payment on top of your pay. This bonus is based on the years served increasing annually for your first 5 years.
If you join a specialist unit the days required to qualify for the bounty could be as little as 19 days a year.
This might sound like a lot, but broken down over the year, it could be as little as:
32 x Weekly drill nights ¼ day = 8 days
1 x Annual camp = 15 days
2 x Training Weekends (these are usually held monthly) = 4 days
You can do more training if you like - you're paid for each day you do so it's a good way to earn extra cash. In fact, many people enjoy it so much they find that they spend at least 40 days a year with the Army Reserve.
The great thing is that you can fit most of your training around your day job. You do it in the evenings and at weekends. There's also a two-week training camp each year. Apart from the camp, it's up to you and your unit to decide how much training you do.
The Joining Process
Find out more about how to join.
Find your local Army Reserve Centre