Really you'll save some cash only because you won't have to hire a professional moving company. You won't be able to avoid any other outlay but if you have to consider a tight budget, saving just a bit is better than nothing.
2. Is it really a waste of time?
A lot of people would tell you that hiring a professional London man with van company is much better option, especially if you don't have much spare time. Although you may succeed is saving a couple of pounds if you prefer DIY removals, shouldn't forget their main drawback – they require a lot of spare time. Bear in mind that you won't be able to pack as fast as a pro your belongings and definitely it won't be so qualitatively.
As you could see, that are two conflicting opinions and you have to think about which is the most favourable option for you – to hire a professional man with van from London or to cope by yourself with your relocation. It's only up to you but I would advise you to think out your decision and consider all pros and cons before taking any action.