TV money goes into your balance in installments, there will be no lump sum in pre-season.
Arranging friendlies against high rep sides(I also got some dutch sides for my Wrexham game in the lower English Leagues) makes alot of money, but heavy defeats can lead to poor morale going into the season so I'd suggest playing a couple of weaker teams too.
Try offering all your players slightly reduced wages/bonuses. Often most will accept slight drops,some older players tend to accept substantial drops in my experience.
Ditch some scouts or physio's if you don't really need them.(do you have a large enough squad to need more than 1 physio)
Sell off players who rarely play(or even make the bench) even if its for free just to get them off the wage bill.
Ask for large sell on clauses when you sell players, especially the free sales, most clubs will still make the offer.