When starting a new job in Spain for a Spanish company, do you need to provide any kind of documentation from the Uk to the new spanish employer for tax purposes ie P60 etc?

I can only speak from my own experience but I wasn't asked for one, no.

no, but residents card, padron,NIE, your employer should get you regitered with the Hacienda and Seguridad Social, ( known as "la Alta") you will get a SS card in the mail after a while.

You mean there is a job to apply for..wow? You already have the lucky charm no need of P60s as most people in Spain have the P45...

I do not know but if you have the offer, very well done to you.

I would think not, surely a P60 is a UK tax form.
When you move to Spain you will be entering a new tax regime - one that starts on 1st Jan not 6th April. Allowances will be different and IIRC my BH was "marginally taxed" whatever that is, until the end of the first year when she had to fill in a tax return.
Dependent on when you actually leave the UK, you may even be able to get a small tax rebate from the UK.

There are taxation differences in Spain, they even allow you to claim a small allowance against your rent - providing your landlord has reported the income on his return, and some medical expenditure. They can be quite complex and the tax form is only in Spanish, so needs to be read carefully.

I would have thought you new employer would be able to assist with information such as this, as they will have to pay a "national insurance" payment for you which will cover your medical and social security.
These items will have to be arranged when you get over here along with an NIF registration. Dependent on where you are as to how long all these things take, but with a bit of planning I managed to get it all done inside 3 weeks including all the form filling etc. The hardest bit was the registration with the doctors and the issueing of the medical card that is universally used. (But others will have managed better service on that)
But you will have to get it all done ASAP as your employer may not be able to pay you until you are registered fully.

Good luck and please keep us informed on how you are doing.