Re the insurance thing, they all do that with renewals now it seems, you’ve surely had it with car or household policies? If you’re not prepared to shop around each year then you get stung with the “loyalty premium”!
Buying a new wagon though… 
I think a lot of O/D’s and small hauliers are in a similar position. Low emission zones in all cities will mean investment in EURO6 trucks. Incentives are unlikely, because of commercial advantage. Why not tough it out? Trade through, and wait for EURO6 used trucks to be more affordable. I have a similar age truck, and have it contract maintained. Okay, you will get the odd bill for pieces that wear out, but that will be far less than a full price rental/lease purchase payment truck for even 3mths. You are already wise enough to know turnover is vanity, profit is sanity and cash flow is of course reality. Best of luck for whatever you decide to do.
Tarmac duck:
That is the end of being an owner driver operating a rigid tipper. After 25 years I have reached a point where I am stuck in a 5+ year old truck that I cannot afford to replace. It would cost approx 15k more than my current wagon it would carry less wieght, burn more adblue and I feel be much more trouble some, all for similar rates which I worked for 5 years ago. Any body looking for an experienced driver with a clean license (36years) ?
If this is accurate description and I well believe it is, then get out while you can. It should not be your problem if payload is less or costs rise due to adblue, new regulations etc. You have to pass new costs onto your customer and they pass it on to their’s etc. because anything else is unsustainable. If they are unwilling to accept that economic fact then walk away while you can and leave their product on the floor.
While there are enough idiots willing to play their game and work for nothing things will certainly not improve. Entrepreneurial risk without entrepreneurial reward is just vanity or folly.
Write a nicely worded letter to all your old customers thanking them for their past business and mention a few pertinent facts to explain why you are withdrawing your services for now.
The next 12-18 months will see lots of change and high risk I believe. I would hate to have large monthly financial commitments hanging over my head during this period as then you are obliged to play on their terms just to keep the wheels and cash flow turning.
On one hand it seems the economy will slow down a bit after Brexit so work may slacken off a bit for a while although one good building project locally could offset that.
On the other hand I do see the driver shortage having a big effect in this period and thus O.D.’s should get a bigger share of the market as they can guarantee delivery but will they be clever enough to negotiate proper rates from their now fortified position■■?
The container industry is on its knees already mainly due to a driver shortage and an IT hiccup in Felixstowe but have rates improved much just yet?
So if current rates really don’t make the grade get out for now and try other things. Keep your eye on the industry and if you see things changing favourably you can always get back in. If I am right about a driver shortage a lot of gear will be parked up or for sale at a discount soon enough.
Know what rates and credit terms you are happy to work for and if and when you can get customers at those rates you should be able to get back up and running quickly with your experience if you feel so inclined.
As others have said getting out on your terms while ahead is good for the mind and the wallet and getting back in has to be on your terms or better also.
That’s my 2 cents worth but I am just an employee myself and not a businessman.
I love the idea of owning 3-5 trucks and perhaps I should have tried that years ago but I don’t have the hunger, the guts, the naivety or whatever it takes to start that now so I wish you the best of luck whichever road you travel.