From north to south:
Inverness to Aberdeen
Inverness to Dunblane
Craigendoran Junction to Mallaig and Oban
Norwich to Great Yarmouth and Lowestoft
Won't happen full stop as I don't believe the BCR stacks up so doesn't present a good business case for electrifying because if you wire up the West Highland then you might as well wire up the Far North lines which won't happen.
From north to south:
Crewe to Llandudno and Holyhead
Aberdeen to Edinburgh
Thornton North and South Junctions to Inverkeithing via Dunfermline
Newcraighall to Tweedbank
Glasgow Central to East Kilbride and Carlisle via Kilmarnock
Newcastle to Carlisle
Newcastle to Middlesbrough via Hartlepool
Bishop Auckland to Saltburn
Middlesbrough to Battersby (tram wire similar to Wolverhampton - Oxley Depot)
Carlisle - Whitehaven
Oxenholme - Windermere
Carnforth to Barrow-in-Furness
Preston to Leeds via Bradford Interchange
Preston to Ormskirk
Bolton to Colne via Blackburn
Kirkham & Wesham to Blackpool South
York to Leeds, and Leeds to Selby
Leeds to Sheffield via Wakefield Kirkgate
Leeds to Guide Bridge via Huddersfield, plus Ravensthorpe to Knottingley via Wakefield Kirkgate, and Mirfield to Halifax/Hebden Bridge
Doncaster to Sheffield and Doncaster to Kingston upon Hull via both Selby and Goole
Doncaster to Scunthorpe
Sheffield to Stockport, plus Hazel Grove to Buxton
Sheffield to Nottingham via both Derby and Alfreton
Chinley to Manchester Piccadilly via both Bradbury and Hyde Central, plus the Rose Hill Marple stub
Southport to Bolton and Salford Crescent via both routes, plus Kirkby to Wigan Wallgate
Warrington Bank Quay to Chester via Frodsham
Helsby to Ellesmere Port
Bidston to Wrexham Central
Chester to Wolverhampton via Wrexham and Shrewsbury
Stoke-on-Trent to Derby and Matlock
Shrewsbury to Cardiff via Hereford
Craven Arms to Knighton (using tram wire, although unsure if there is a tunnel before or after Knighton, plus saves having to change power modes on the main line assuming bi-modal trains are used)
All former Great Western Railway routes in the West Midlands
Oxford to Bedford Midland (and onwards to Cambridge if that section is ever rebuilt)
Peterborough to Ely
Norwich to Ely
Ely to Stowmarket
Ipswich to Felixstowe and Lowestoft
Valley Lines Network in Wales
Bridgend/Pen-y-Bont to Swansea/Abertawe
Although a very lengthy post, in short, I would like most if not all routes electrified north of the M25, especially the east-west axis routes.
Crewe to Llandudno and Holyhead won't get done in full as the BCR isn't high enough with a acceptable business case so likely only Crewe to Chester will be done.
Thornton North and South Junctions to Inverkeithing via Dunfermline should be done the same time as Edinburgh to Dundee via Kirkcaldy and Cupar as again I don't believe there's a good business case for wires from Dundee to Aberdeen unless it can be proven that it is.
Newcraighall to Tweedbank again the business case and BCR isn't high enough but electrifying this line would mean no DMUs in the Edinburgh/Central Belt area so makes sense as a infill but only if the existing infrastructure is used to the maximum possible.
York to Leeds, and Leeds to Selby seems good to do however why not also include York to Selby and onto to Hull that way which would make far more sense.
I note you state "Ely to Stowmarket and Norwich to Ely" so why not Cambridge to Ipswich too as that would mean Greater Anglia running EMUs on the local stoppers.
Ipswich to Felixstowe and Lowestoft will only be done to Felixstowe to allow for more electrically hauled freight, Lowestoft won't be done at all.
I also note you haven't included the Peterborough to Birmingham line via Leicester and Nuneaton which as I said in a earlier post would mean the end to 2 and 3 car DMUs and instead use 4 car EMUs on a 30 minute frequency on the line which would vastly cut down on overcrowding.
