Parts are readily available on ebay & eurocarparts, you can even buy parts from Lexus Birmingham on Ebay.
Oil and oil filter & o-ring / gasket are easy to change yourself for ~ £50
Intake & especially the pollen filter are very easy to change for £25.
Brake fluid full flush in half an hour if you have a mate for £15. Plenty of videos on Youtube about this.
Differential fluid I've not done, but it's not hard so long as you have the kit to get under the car safely. Topping up the transmission fluid is similar.
Checking battery fluid level (if applicable), start time, tire wear, coolant level, lights on the dash and working exterior lights is very easy.
Checking the brake disk wear can be done without taking the wheels off, same for pad wear. Replacing these is easy so long as you have axle stands / a big block of wood. Parts as above.
Check the brake pedal height from the carpet (16.4-17.4 cm) and that the brake position when pressed is well clear of the carpet. The parking brake needs 10 cm from the carpet when applied with normal force.
Tyre pressure you should be checking anyway, and check for damage.
When doing the above, have a good look around for anything else that looks worn or overheated. Wheels shouldn't wobble or rattle, steering should be firm and responsive, tyre wear should be even, exhaust hangers shouldn't be rusty, shocks shouldn't be leaking oil, the oil you drain shouldn't be gritty / foamy / pale.
DPF / EGR I can't advise you on as I don't have a diesel, but it's discussed on here a lot. If you're seeing good mpg then you should be okay.
As for the 'usual checks', Tunbridge Wells is a long and unpleasant drive for me, so I used a local high end specialist who have a much longer checklist as well as lower costs.