want to travel to iran by train from uk?

any input from anybody

See really good website on the link below that will tell you how to do this.

I don't think you can. It is possible (just) to travel from the UK to Syria, via Turkey, but I don't think there are any links into Iran.

That's brave! It's pretty straightforward getting from London to Istanbul - it takes between 58 and 65 hours to get from St Pancras to Istanbul Sirkeci, then you have to get across the Bosphorus to Haydarpasa station in time to catch the one train per week that goes to Teheran, the Trans-Asia Express - it leaves Haydarpasa at 2255 on Wednesday night, and is scheduled to arrive in Teheran at 1920 on Saturday (actually, the Turkish train travels to Tatvan, on Lake Van, then there's a five hour ferry journey to Van, then you pick up an Iranian train to travel the rest of the way; only the baggage van travels all the way from Istanbul to Teheran, being carried over on the ferry).

You would be wise to allow a day for the connection in Istanbul (and you must allow a day when you're travelling westbound), and expect to be several hours late arriving in Teheran. The westbound train leaves Teheran at 1900 on Thursday, and arrives in Istanbul at 1545-ish on Sunday. There is reputed to be a second weekly train in the summer, but no-one knows when it runs!

You will, of course, need a visa to visit Iran, and they're not always granted to independent travellers.