Hi Lee currently there is no such thing as a mortgage rate reference website. Following on from Claires comment they change terms and conditions as frequently as they change their underwear ...... simultaneously not publicising what the changes are.
However to try and give you some insight - generally most lenders follow Annual Euribor on the day of purchase completion (realistically this would be the rate published on the first of the month) plus whatever margin above that the bank charges. What this means is that you effectively have a one year rolling fixed rate. The rate is fixed for 12 months and just prior to the anniversary of completion it is set for another 12 months and so forth for the life of the mortgage.
Fixed rates are generally unpopular with the Spanish. Owing to banking restrictions on arbitrage they are not permitted to hedge the risk. Thus they will consider long term money markets and the overall risk of what rates might do. Then they "stick their finger in the air" to see which way the wind is blowing and will offer a rate between 2 and 3% (in personal experience) above the standard Euribor plus calculation. They are only ever considered by special request and dont have a published portfolio as rarely do people take them.
Many lenders will insist that you take out their life insurance - some of them on a single premium basis (i.e. a policy costing several thousand Euros which will provide life cover for the term of the loan so be careful of this - for many lenders it is a deal breaker despite the fact it is actually illegal to insist you take their in-house life cover - however they are permitted to decline you the mortgage if you dont want their life cover.......you work it out!). There are some that will permit you to cancel the life cover after the first 12 months but this will incur an increase in the margin above Euribor.
Currently the market is running between 1.8% and 3.5% ABOVE 12 month Euribor subject to loan to value, terms etc. Be careful of lenders offering the old method of interest charging - for the life of me I cant remember what it is called (Alzheimers is setting in 
) at the moment and most lenders have abandoned it, but it would probably be polite to call it abusive and many years ago I asked a bank that applied it to explain to me how it was calculated to agree to their published rate of (at the time) 4.5% and the physical interest (in money) that was charged on a ten year illustration was closer to 7% p.a.
You can view up to date Euribor settings at http://www.euribor-rates.eu/ or at the ECB's own page or the Bank of Spains page but the link provided is an easy site to navigate.
Hope that helps.......albeit maybe only a little.