How can I rename a table, but also all FK etc. references to that table?
You should be able to generate the appropriate rename scripts using this, and adjust it to whatever naming convention you choose;  I've used this to ensure that the names use the current table and column names, so the where clause currently finds names that don't follow that convention.

SELECT
    PK_Table = PK.TABLE_NAME,
    PK_Column = PT.COLUMN_NAME,
    FK_Table = FK.TABLE_NAME,
    FK_Column = CU.COLUMN_NAME,
    Constraint_Name = C.CONSTRAINT_NAME,
    'FK_' + FK.TABLE_NAME + '_' + PK.TABLE_NAME + '_' + CU.COLUMN_NAME,
    'sp_rename ''' + C.CONSTRAINT_NAME + ''', ' + '''FK_' + FK.TABLE_NAME + '_' + PK.TABLE_NAME + '_' + CU.COLUMN_NAME + '''' + char(13) + char(10) + 'GO' + CHAR(13) + CHAR(10)
FROM 
    INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
    INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
    INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
    INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
    INNER JOIN (
        SELECT i1.TABLE_NAME, i2.COLUMN_NAME
        FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
        INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2 ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
        WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
        ) PT ON PT.TABLE_NAME = PK.TABLE_NAME
WHERE
    C.CONSTRAINT_NAME != 'FK_' + FK.TABLE_NAME + '_' + PK.TABLE_NAME + '_' + CU.COLUMN_NAME
ORDER BY 
    PK.TABLE_NAME, FK.TABLE_NAME