Hi Grumpy,
When you take your pension commencement lump sum (25% tax free), you will be crystallising your pension, you have a few options in regards to the remaining funds in your pension but if your looking to take another 30/40k then you'll be after drawdown. I would strongly consider your timing as key, as 30/40k would likely push you to a higher rate tax payer (if you aren't one anyway), so you could've taken 20k by 5th April 2017 and then another 20k in the new tax year.
If you go drawdown, check the past performance of the funds, sometimes too much attention is given to charges, no point paying low charges for rubbish performance as it'll cost you more long term. You get what you pay for in this world.
Hope this helps