I have over the last week spoken to my accountant and also looked into this myself,please note you do NOT get 100% back on a van however you buy it ever.If you are VAT registered you can claim 100% of the VAT back but for the balance you are still only able to claim a percentage of it normally 40% in the first year,if your not VAT registered the best way to buy a van and the cheapest for you is to buy it on HP over the period which you can afford,all this you can claim 100% back on the van is complete rubbish do you honestly think the government would stand for that.The only thing you will get back 100% is the VAT and to do that you have to be VAT registered,if your not VAT forget contract hire and lease.
You're not getting 100% of the purchase price back dude, this 100% thing referes to the amount of capitol that is tax deductable & depending how you buy/lease a van depends on how this will work out. e.g.
If you lease a van the monthly payments are 100% tax deductable, which means that you won't pay any tax on that amount. This is providing the van is used 100% for your business. so, if after a year you have paid out 1400 quid in lease payments, you won't pay income tax on that 1400 quid, which will (@ full amount) save you about 300 quid. It doesn't mean you get 1400 quid back

What people are refering to is an amount (or %) that you will not have to pay tax on & not an amount that the tax man gives you back (although that would be nice).
One example where a deduction (the amount to knock off) off your year end profits is useful for some is if that person recieves any benefits, like child tax credits/working tax credits etc. the lower your profit the more benefit you recieve in a lot of cases.
So it's not always just down to the amount of tax to be saved but also benefits to be gained.
tony